Lay subfloor over moist concrete under Pergo???

I got one third of a Pergo floor laid on a concrete slab living room floor before I realized that I needed to do a moisture test (a miscommunication: I was led to believe that since the floor was 30 years old and had previously had carpet over it, then the concrete would have completely cured, etc.). As it happens, the concrete appears damp under the section that I've laid so far.

Anyway, I am faced with the prospect of tearing up the floor, or finding a way to continue and somehow mitigating the excess moisture in the concrete.

Can anyone PLEASE offer some advice on any or all of the following concepts?

(1) I could apply some sort of concrete sealant (e.g., Drylock), and continue to lay the floor;

(2) I can seal the floor as above and then lay a plywood or other subfloor over the concrete. I would sandwich the plywood floor between layers of 4-8mil plastic sheets.

(3) Seal the floor, lay a linoleum flooring, and then proceed with the Pergo.

things may not be as bad as you think.#1....did you put the 2 in 1 foam under the pergo? (2 in 1 foam is the foam with a plastic sheet on one side foam on the other)if so moisture may not be a problem.did you do a moisture test? a simple one is to tape a plastic bag (a big one) to the floor with duct tape,wait 48 hrs pull up the bag an see if it has droplets of water under it.dont worry about the "professionals" they dont want to sell the same product home depot sells because they cant touch the price (pergo invented laminate flooring,and has over 20 years of experence with it) it's as good a product as any out there.please post your reply. thank you

Pergo Presto is a click together floor if I'm not mistaken. Since it's not glued together you can simply reverse the process you did to install it and not damage the flooring. This means you simply lift each board so it unclicks, do the moisture test, take any corrective measures like poly film and reinstall the same flooring.

They say the flooring can be put together and taken apart about 3 times without compromising the structural integrity of the click system. If your flooring is older and it is glue together that is more permanant.

Yes, I am using the 2-in-1 underlayment. There are two rows of underlayment on the floor. The concrete under each row is darker than the section with nothing on the concrete. Moisture clearly is building up under the underlayment.

I did not conduct a moisture test. I found out about the moisture when I had to move my unused stack of Pergo packages out of my workspace. The plastic on the packaging was wet underneath. So, I haven't, as yet, figured out "how much" water the concrete is giving off.

I am currently conducting an experiment by putting two squares of linoleum on a bare section of the concrete. One square has a sheet of plastic over it, taped down, just as for the moisture test. I want to see if moisture builds up on or around each square.

If the linoleum elsewhere in the house is intact and impervious to water from the concrete, would laying linoleum under the pergo (and underlayment) be enough to mitigate the moisture?

You never mentioned if the concrete you're trying to install Pergo over is a basement or not. I suppose it doesn't matter. There is a product that you can order that is meant for basement subfloors, but it's basically engineered to let the concrete breathe. Being in Hawaii will complicate getting this to you. You'll have to pay freight, which will add several hundred to your cost, but it's worth it. Look at http://www.dricore.com (about $6/panel US), http://www.subflor.com (about $6.50/panel US) or http://www.deltams.com/deltafl/ (not sure of the cost but it's less than the first two I'm sure).

The Dricore and Subfloor are the easiest to install. A lot like Pergo Presto in fact. The Delta FL will be lighter and cost less to ship, but you'll have to install OSB plywood over top to achieve the same effect as the other two products. Good luck.

Thanks, that's the best piece of news/advice I've heard yet. The Delta-FL sounds the most intriguing (as it would be easiest to ship).

No, this is not in a basement. It's actually our living room. The suggestion has been made that there may be a pipe leak under the slab somewhere. I think it is more likely that the piece of land on which our townhouse is situated is a peninsular surrounded by water. We suspect that the ground is essentially landfill made up of dredged material from the bay. The houses are 30+ years old. This could explain hydrostatic pressure from underneath the slab.

What is surprising is the reaction that we get when we call contractors and flooring specialists and put the two words "Pergo" and "moisture" in the same sentence. One guy said he wouldn't touch this project with a ten-foot pole.

Thanks for the advice. I appreciate any extra thoughts anyone might have on the subject.

FYI, I just found out how much the Delta FL product would cost. A distributor here in Seattle has it in stock, and they quoted me $169 for a 5' wide 55' long roll. Then I went to the website and saw that this product works well with laminate in that you don't even need to install OSB or plywood overtop. Just let the whole system float. For me, this option cuts my price in half. My basement is approx 328 sq feet and would cost abut 650 to do in Subflor. I want carpet, so I have to get the Delta FL and OSB making the cost about $350 total. I'm starting to consider installing laminate to save money. I was going to put the laminate upstairs anyway. I wonder if you could get this Seattle company to ship to you. Here's the info from the website...

Thanks to all who offered their advice on my floor problem. I thought I would provide an update. The Pergo floor is laid and looks great. I did order the Delta-FL subfloor and laid it under the Pergo.

It all went together pretty well, except the dimples on the Delta FL does not interlock as well as the company suggests it should. Also, the Delta-FL was somewhat noisy. It sounded like someone was walking in soccer cleats on a concrete floor. So, I contacted the manufacturer and they suggested that I lay some polypropylene landcaping fabric under the Delta. It's a little strange, but it works.

Okay, one thing to remember when using the Delta-FL is that it raises the level of the floor. This makes installing the transition moldings a bit tricky. I got around it by simply installing thicker slate tiles next to the Pergo floor (as opposed to our original plan of using ceramic tiles).

When all is said and done, the floor looks great. I probably would recommend any other brand instead of Pergo, if anyone were to ask me, for two reasons: One, I thought their non-responsiveness to the problem in the first place was, well, non-responsive. I bought $1,000-worth of their product and their best solution was to suggest that I NOT lay their product. Two, I have since seen some other brands being laid and feel that they go together easier and tighter than the Pergo Presto.